ATC  never heard of it? Then it's time to change that!
Otherwise you might possibly miss the best loudspeaker of your life  as for
example the SCM150ASLT active floorstander.

Professionals At WorkYou might think our introductory statement to have been rather
bold, which, of course is absolutely possible. However on the other hand there
is the list of people using ATC speakers, which reads like the Who's Who of
worldwide recording studios, musicians and producers. You're not easily
impressed by names? Wonderful! Then you are probably someone who likes to make
up their own mind and who treats the unknown with equal amounts of openness,
curiosity but also skepticism.

The big question is why a product like this has not yet made
it into the general awareness of hi-fi and music lovers all across the world?

Certainly Not MainstreamIf you place the ATC SCM150ASLT next to one of the many
graceful loudspeakers that normally populate our listening room, a faint
suspicion arises as to what could be the reason for ATCs limited prominence:
could it be that the look is perhaps too far from the mainstream? Is it just too
independent? If so, that's what ATC is all about, because the technology is by
no means standard either. Instead, chassis, crossovers and even the amplifier
electronics are developed and built in Gloucestershire by ATC themselves with a
breathtaking range of in-house production.

Founded in 1974 by Billy Woodman, the British started to
develop chassis for professional sound systems. The abbreviation ATC  which
stands for Acoustic Transducer Company  also stems from this origin.

The first chassis was a 12-inch bass driver, which was
followed in 1976 by the mid-range chassis, which established the company's
legendary reputation for its huge dome shape. We also find a current incarnation
of this legendary midrange driver in the ATC 150 and some other models of the
manufacturer. Not surprising, since this dome covers the frequency range from
300 Hertz to three kilohertz with lowest distortion and very large sound
pressure reserves. Right down to the magnetization, the driver is completely
manufactured in-house and is strictly selected. Some other manufacturers have
emulated the British over the years and designed similar looking domes, but the
original is still manufactured at ATC.

Active From The Start

Since 1978 they have been producing speakers  which were
already prepared for real tri-amping at the time. They could even be switched
between passive operation via the built-in crossover or active operation via
external crossover. One basic idea remained the same for all models, whether
active or passive: the timbre and tonal color should always be similar, even in
multi-channel applications such as those found in the Sony Music Studios in New
York.

To ensure that their ideas were implemented consistently,
the British created comprehensive specifications. As expected, these include a
linear frequency response and low distortion. However they also included a phase
response as even as possible and a uniform radiation pattern. Timing accuracy
and a linear frequency response, elsewhere often implemented by DSP, are
generated by the individual drivers and also by the sophisticated active
analogue crossover concept. Currently available DSPs can correct the frequency
response on axis  but the effects off axis remain incalculable  and in
most cases they become significantly worse. Of course, this has an effect on the
portion of sound that is reflected from the room and also reaches the listener's
ears  albeit late. The result is often a considerably discolored, unnatural
sound image.

Special attention is always paid to the transition area
between the drivers, where the greatest source of danger for falsifying the
natural sound is found between the midrange and bass drivers.

When it comes to phase response, the developers' main concern
is to ensure that no abrupt changes in frequency occur, which in the experience
of ATC is an unmistakable indication of driver resonance. All the more reason to
take the chassis development and production into their own hands and ensure that
high and low-pass filters have the same phase response.

Timing errors are considered to be a cause of obtrusive sound
that quickly causes fatigue in the listener. The careful design of the drivers
and crossover network as well as intensive damping of the diaphragms
counteracts this.

Dynamics Without LimitsSince every detail in loudspeaker design is connected to
everything else, the relationship between magnetic flux and the real-life
temperatures at the voice coil has of course been investigated, as well as the
mechanical stability of diaphragms and the spring system. It's easy to imagine
how important dynamics are when you know that even a seemingly harmless string
quartet can easily generate a good 100 dB of sound pressure at a distance of two
metres. The total amplifier power of 350 watts  2/3 of which is entirely in
Class A  is fed to the drivers with almost no distortion. Enough to let the
38cm bass driver pump even the deepest frequencies into our room with majestic
composure. It should be noted that, on top of that, active speakers are on
average six decibels more efficient with amplifier power than passive speakers.

The broad-shouldered British speaker let us feel this
efficiency from the very first second when Ray Brown's masterpiece "Soular
Energy" or "That's all Piano" with Gene Harris played. It was a
performance that awakened memories of accelerations previously only experienced
in supercars, only to bring the shimmering impulses to a complete stop in the
next moment. Brown's double bass stood large and voluminous  though without
the slightest inclination to drone  as well as vivid in height, stage width
and depth and yet sharply outlined in front of the audience.

It is noticeable that the sound image  in contrast to what
is often experienced especially with electrostatic transducers  is not
projected from the loudspeaker level to the rear but to the front of the
listening room. To make the happiness complete: this is achieved without ever
being annoying at all  even at levels far beyond the 100 dB mark. The
resolution displayed by the fabric dome tweeter does not gloss over anything and
makes many a ribbon fan doubt his lovingly cultivated dogmas. But don't worry,
neither in Frank Sinatra's "Live at Sands" nor Lyn Stanley's latest
opus "Live at Bernie's" the richness of detail comes at the expense of
enamel and grace - as long as all components are carefully matched and the
recordings are faultless.

If you like it a bit milder and a bit less precise  maybe
because your system or the music you are currently listening to does not meet
the highest demands  you should angle the 150 a bit less. This won't do any
harm to the dynamic capabilities, which always seem relaxed and effortless
especially on live recordings, but it did make for a little gentleness on the
remastered garage sound "Monster" album by R.E.M., for example. Such
emergency measures were superfluous, however, for example with the
"Original Trinidad Steel Band" and the album of the same name, which
was full of timbres, showed impulses in abundance and one hardly knew where to
direct one's attention because of all the different sources of sound.

Between Delicate And PowerfulBelafonte at Carnegie Hall showed all facets of this
extraordinary singer and entertainer and the "Cotton Fields" made you
forget that the recording was made in 1959. The passion with which the American,
subtly but effectively supported by the bass, performs his songs is simply
impressive.

If you've always wanted to hear a clarinet, "El Choclo"
and "Maria", played by Giora Feidman, captured live in a New York
church, with their gentle, almost tender wind sounds, are the ideal
introduction, especially since the guitar sounds played along with them are
perfectly integrated.

Puccini's "La Boh่me", recorded in 1974 by
Karajan's Berlin Philharmonic Orchestra and starring Luciano Pavarotti in the
role of Rudolf, provided the "Ice Cold Hand" with Pleasant shivers,
not least because the stage on which the action took place was very easy to
understand. When we returned to the "lowlands" of popular music to
hear Montserrat Caball้ and Freddie Mercury with "Barcelona" and then
"Heaven" sounded powerful and passionate as well as full of
"heavenly air"  it almost moved us to tears. This loudspeaker can,
despite its high price, be regarded as almost incredibly cheap for what it has
to offer. Something that has unfortunately become an exception in the world of
high end audio.